| dc.description.abstract | Gravity observation is one of priority method that used to explore the subsurface structure. Because it is easy, fast and low-cost, dense gravity observation stations are distributed in whole Taiwan, no exception in mountain area. In this study, the message contained in the observation of gravity values is analyzed. We use g-H relationship and Nettleton′s density determination method to estimate the density of topography. Based on the results, the density value of mountain area ranges from 2.4 to 2.6 g⁄〖cm〗^3 , is 2.2 g⁄〖cm〗^3 in Western Foothills and 1.8 to 2.0 g⁄〖cm〗^3 in Western plains. After gravity correction, we can get Bouguer anomaly value and separate the source of gravity effect to the shallow and deeper part from gravity wavelength. Then, it led to discuss the Moho interface relief and subsurface density distribution. The shallow gravity effect is consistent with the pattern of geological division. The deeper gravity effect map reveals that the gravity low area is existed beneath Western Foothills, it might relate to crustal thickening. We utilized the empirical relations between elastic wavespeeds and density to analysis the consistency between velocity structure and observation gravity. According to analysis and comparison, there are significant differences between the analytical results of two physical properties observations.
In this study, we begin from two-dimensional co-simulation modeling method using TAIGER, ATSEE TSEE of seismic data and observation gravity data. Then, the theoretical travel time and gravity value is calculated from three two-dimensional cross-sections across northern, central and southern Taiwan. The results of forward modeling that correspond with travel time and observation gravity and large scale Moho interface relief can be use as better initial model of three-dimensional subsurface modeling. | en_US |